The invention relates to an apparatus for recording an electric signal on a magnetic record carrier in tracks which extend parallel to each other in a track direction and are inclined relative to the longitudinal direction of said record carrier, and to an apparatus for reproducing the electric signal from said tracks.
A recording apparatus of the type defined in the opening paragraph, comprising
an input terminal for receiving the electric signal, PA0 a signal source for supplying tracking signals, PA0 write means having an input coupled to the input terminal and to an output of the signal source, for recording the electric signal and the tracking signals in a track, which write means comprise at least one write head arranged on a rotatable head drum, is known from U.S. Pat. No. 4,297,733. The tracking system used in this known apparatus is the well-known four-frequency DTF system employed in the V2000 video-recorder system. In this system the video signal is recorded in analog form and for the purpose of tracking the four tracking signals of different frequencies are each time recorded in a cycle of four consecutive tracks. PA0 read means for reading from the tracks information comprising the electric signal and tracking signals, and for applying the information to an output, which read means comprise at least one read head arranged on a rotatable head drum, PA0 detection means for detecting the tracking signals from the information read from a track and for generating a control signal from the detected tracking signals, having an input coupled to the output of the read means, and an output for supplying the control signal, PA0 positioning means for controlling the relative position of the read head in a direction transverse to the track under the influence of the control signal, which positioning means have an input coupled to the output of the detection means, and PA0 an output terminal for supplying the electric signal, is characterized in that the read head comprises two head halves which have a mechanically rigid coupling with each other and which are constructed to read information from both track halves of a track, in that the detection means comprise a first and a second detection unit, each having an input coupled to the first and the second head half respectively, which first and second detection unit are constructed to detect the crosstalk of the second and the first tracking signal respectively from an adjacent track half, in that the detection means are further constructed to derive the control signal from the detected first and second tracking signals, and in that the apparatus is further constructed to derive, by combining the information read from the associated track halves by the first and the second head half, the electric signal from said combined information and to apply said signal to the output terminal. PA0 1. During reproduction the head follows a track in which no tracking tones are recorded. The crosstalk of tracking tones from the adjacent track halves of the adjacent tracks are now detected and the position control system positions the reproduction head in such a way that the crosstalk is of equal magnitude for both tracking tones. PA0 2. The head follows a track in which the tracking tones are recorded. The tracking tones in the track being reproduced are employed. The crosstalk of the tracking tones from the adjacent track half of the same track are now detected and by suitably positioning the head relative to the track the crosstalk is equalized for both tracking tones. PA0 1. During reproduction the head follows a track in which tracking tones are recorded. The tracking tones in the track being reproduced may again be employed for following this track. The crosstalk of the tracking tones from the adjacent track halves in the same track is detected. PA0 2. The head follows a track directly succeeding a track in which the tracking signals are recorded. Now only one of the head halves can detect crosstalk from the adjacent track half of the preceding track. If moreover the detected tracking signals from (a plurality of) preceding tracks are allowed for and averaged it will also be possible to derive a tracking control signal for this track. PA0 3. The head follows a succeeding track. Now only the other one of the two head halves can detect the tracking signal recorded in the adjacent track half of the succeeding track. Again it is possible to derive a control signal which enables the relevant track to followed by averaging the tracking signals detected from (a plurality) of preceding tracks. If the crosstalk signals are recorded in every n-th track, n.gtoreq.4, a head will also scan tracks in which no tracking signals are recorded and in whose adjacent tracks no tracking signal are recorded. For such a track tracking is also possible, namely in a manner as described hereinbefore, by deriving for those tracks in which no tracking signals are recorded a control signal from tracking-signal crosstalk detected from those track halves in which tracking signals are recorded. By utilizing the control signal thus obtained also for those tracks in which no crosstalk of tracking signals from adjacent track halves can be detected, it is implicitly assumed that the shape of these tracks on the record carrier is more or less identical to the shape of those tracks from which tracking-signal crosstalk from adjacent track halves can be detected.
Said system has proved to be of very high quality.